Traditionally, tractors have been known as typical working vehicles (see Patent Literature 1; hereinafter PTL 1). Each tractor has a transmission that enables changing of the traveling speed. Further, the transmission is provided, in addition to the speed changing mechanism, with a front-wheel drive mechanism or a work-machine drive mechanism.
The transmission has a hydraulic unit which operates with a working fluid (see Patent Literature 2; hereinafter PTL 2). Therefore, in the transmission, a pipe for supplying the working fluid is connected to the hydraulic unit, which caused a complex structure with a large number of components. In view of this, there has been a demand for a transmission which can improve the productivity and reduce the costs by reducing the number of components and simplifying the structure.
Further, the transmission has a hydraulic pump configured to pressure-feeds a working fluid. Therefore, in the transmission, a pipe for supplying the working fluid is connected to the hydraulic pump, which caused a complex structure with a large number of components. In view of this, there has been a demand for a transmission which can improve the productivity and reduce the costs by reducing the number of components and simplifying the structure.